Nowadays, many detection and analysis methods for determining physiological parameters in samples of body fluids or in other biological samples are carried out in an automated manner and in large numbers in automatic analysis appliances or so-called in vitro diagnostics systems.
Today's analysis appliances are able to carry out a large number of detection reactions and analyses with one sample. To be able to carry out a large number of tests in an automated manner, various devices are needed for the spatial transfer of measurement cells, reaction containers and reagent containers, e.g., transfer arms with a gripping function, transport belts or rotatable transport wheels, and devices for transfer of liquids, e.g., pipetting devices. The appliances comprise a control unit which, by means of suitable software, is able, largely independently, to plan and work out the work steps for the desired analyses.
Many of the analysis methods used in such automated analysis appliances are based on optical techniques. These methods permit the qualitative and quantitative detection of analytes, i.e., the substances to be detected or to be determined, in samples. Clinically relevant parameters, such as the concentration or activity of an analyte, are often determined by means of a portion of a sample being mixed with one or more test reagents in a reaction vessel, which can also be the measurement cell, as a result of which, for example, a biochemical reaction or a specific binding reaction is started which brings about a measurable change in an optical or other physical property of the test mixture.
It is known that, in automatic analyzers used to test biological body fluids, the required reagents are introduced into a measurement cuvette by means of a pipetting device with a pipetting needle. The pipetting device additionally has the role of ensuring that the body fluid to be tested is thoroughly mixed with the reagents. For this purpose, it is necessary to set the pipetting needle in vibration. Hitherto, it was possible to set the pipetting needle in vibration only at defined, stationary positions in an automatic analyzer where vibration generators which cannot be moved are provided (see, for example, EP 0994356 A2). This has the effect that the sample cannot be thoroughly mixed at all positions to which the pipetting needle can be driven. Moreover, thorough mixing of the sample is in principle not possible during a transfer of the pipetting needle from a first position in the analysis appliance to a second position in the analysis appliance. This has the effect of taking up more time and considerably reduces the flexibility in the execution of an analysis in an automatic analysis appliance.